The Yamaha PW80 is a small off-road motorcycle designed for younger riders who wish to delve into the fun and excitement of the motocross experience. The PW80 features a 79 cc air-cooled two-stroke engine, three-speed transmission with automatic clutch and a fuel capacity of 1.3 gallons. One of the great features of the Yamaha PW80 is the engine power restriction used to tame the performance of the engine. As the rider gains more confidence and experience riding the motorcycle, the engine restrictor can be removed to allow the motorcycle to operate at its maximum capability.
Allow the engine to completely cool before performing any work to the engine. Locate the two exhaust manifold bolts. The exhaust manifold connects to the underside of the engine, near the foot pegs and by the gear selection lever.
Remove the two exhaust manifold bolts that hold the exhaust manifold to the engine using a ratchet and appropriate-sized metric socket. Pull the exhaust manifold down slightly to expose the round gasket resting in the recess of the exhaust manifold flange.
Remove the gasket and the small restriction washer underneath it. Place the gasket back into the exhaust manifold's flange recess. Mate the exhaust manifold back up to the engine and reinstall the two retaining bolts. Do not overtighten the exhaust manifold bolts, as this will cause damage to the engine.
If you have a torque wrench available, tighten the exhaust manifold bolts to 13.5 foot-pounds to avoid any possibility of stripping the bolt or cylinder head threads.